1. Field of the Invention
The present invention relates to bioengineering technology, and more particularly to a method and device for controlling the fermentation process.
2. Description of the Related Art
The biological fermentation process is a key technique in various industrial fields, such as biopharmaceuticals, biological energy, foods and beverages and environmental protection. An important goal of the biological fermentation process is to improve the consistency of the production process. However, due to the time-dependent change and non-linear properties of the biological fermentation process and the effect of other indeterminable factors, there are often considerable variations among different fermentation batches. How to control the biological fermentation process to deliver high consistency so as to improve the fermentation quality has become an important direction for research.
The biological fermentation process in the present invention includes biological fermentation and cell culture. Industrial biological fermentation processes normally occur in a fermenting tank in which nutrient solution is added and suitable environmental conditions are maintained so that biological cells grow and reproduce in the nutrient solution and produce desired products. The operator or automatic control system can control the biological fermentation process by adjusting the feed rate of the nutrient solution flow to the fermenting tank. In conventional processes open-loop control of the fermentation process is achieved by monitoring and analyzing fermenting environment parameters, such as temperature and pH value of the nutrient solution and concentration of dissolved oxygen, and following a predetermined nutrient solution feeding strategy. However, these control methods only involve external factors such as fermenting environment, but ignore the status changes of biological cells, especially the effect of status changes such as cell size, shape and structure, on the fermentation process. The status changes of biological cells during the fermentation process imposes considerable effects on the fermentation process. Consequently, it is difficult for these conventional control methods to ensure the consistency of the fermentation process.